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The structural and mechanical stability of quasicrystals are important issues due to their potential for possible applications at high temperatures and stresses. The aim of the present work is, therefore, to review the earlier works on conventional crystalline and quasicrystalline materials and also to report the results and the analysis on the Hall–Petch and inverse Hall–Petch like behavior of nanoquasicrystalline Al62:5Cu25Fe12:5 alloys. It was observed that, at large grain sizes, the hardness increases with decreasing grain size, exhibiting the conventional Hall–Petch relationship, whereas for smaller grains, inverse Hall–Petch behavior was identified. The inverse Hall–Petch behavior in the nanoquasicrystalline phase could be attributed to thermally activated shearing of the grain boundaries, leading to grain boundary sliding in nanostructures of quasicrystalline grains. These results were analyzed based on the dislocation pile-up model as well as the grain boundary shearing models applicable to nanomaterials. [ABSTRACT FROM AUTHOR]

The present paper reports kinetic studies of the adsorption of aniline (AN), phenol (P), 4-chlorophenol (CP) and 4-nitrophenol (NP) from aqueous solution onto granular activated carbon (GAC). In FTIR spectral analysis, the transmittance of the peaks gets increased after the loading of AN, P, CP and NP signifying the participation of these functional groups in the adsorption and it seems that the adsorption of AN, P, CP and NP is chemisorptive in nature. The rates of adsorption were found to obey a pseudo-second order model and that the dynamics of AN, P, CP and NP adsorption are controlled by a combination of surface and pore diffusion. The diffusion coefficients were of the order of 10-10 m² s-1 . Thermal desorption at 623 K was found to be more effective than solvent desorption. GAC performed well for at least five adsorption-desorption cycles, with continuous decrease in adsorption efficiency after each thermal desorption. Owing to its relative high heating value, the spent GAC can be used as a co-fuel for the production of heat in a boiler or a furnace. [ABSTRACT FROM AUTHOR]

Presents a letter to the editor about the effect of hot open-die forging on mechanical properties of stir cast metal matrix composites.

Investigates the effect of porosity on the electrical conductivity of the metal matrix composite. Application of composites in the electronic and electrical industries; Difference between the thermal expansion coefficients of the reinforcement and the matrix alloy; Details on the nominal composition of the alloy.